The present invention relates to a switch device in a steering wheel, and more particularly, to a technology for illuminating switch markings on manual switches on a steering wheel.
Typically, the switch device in a steering wheel includes front switches located on the front side of the steering wheel facing the driver (a downshift switch, an audio switch, and a cruise switch), and back switches located on the back side of the steering wheel that is opposite from the front side (an upshift switch). The front and back switches rotate integrally with the steering wheel.
In general, a switching marking provided on each front switch is made of a translucent resin. A light source is provided in each front switch. Light from each light source passes through the marking on the corresponding front switch and directly reaches the eyes of the driver. That is, each switch marking is directly illuminated by the corresponding light source.
For example, an upshift switch, which is a back switch, has a manipulation knob that extends from the back side of the steering wheel to a range visible to the driver. A switch marking is provided on the knob. If a light source for illuminating the switch marking is provided in the knob, the switch marking on the manipulation knob must be made of a translucent resin as in the case of the switch markings on the front switches. Further, the inside light source increases the size of the manipulation knob.
If the manipulation knob is plated with metal, the plated surface reflects natural light in daylight, which improves the visibility of the switch marking on the knob. Therefore, if only the use in daylight is considered, a compact knob having no inside light source may be applied. However, in this case, since the manipulation knob does not emit light, the visibility of the switch marking is low at night.
In Japanese Laid-Open Patent Publication No. 2001-354064, an illuminant is provided on a steering wheel to illuminate a column switch located in the vicinity of the steering wheel. A switch marking is provided on the column switch. Light emitted by the illuminant is reflected by the switch marking on the column switch and reaches the eyes of the driver.
The column switch is located on the dashboard of the vehicle and does not rotate integrally with the steering wheel. Thus, in the above mentioned publication, rotation of the steering wheel changes the relative positions of the illuminant rotated integrally with the steering wheel and the column switch. Therefore, the illuminant illuminates the switch marking on the column switch only in a part of the permitted rotation angle range of the steering wheel. In the remainder of the permitted rotation angle range, the illuminant is incapable of reliably illuminating the switch marking.
Accordingly, it is an objective of the present invention to reliably illuminate a manipulation switch on a steering wheel regardless of the rotation angle of the steering wheel.
To achieve the above objective, the present invention provides a switch device in a steering wheel of a vehicle. The steering wheel has a front side facing a driver of the vehicle and a back side opposite from the front side. The switch device includes a front switch assembly that is on the steering wheel to rotate integrally with the steering wheel. The front switch assembly has a front switch facing the same direction as the front side of the steering wheel. A back switch is provided on the steering wheel to rotate integrally with the steering wheel. The back switch is located at a position closer to the back side of the steering wheel than the front switch assembly. A switch marking is provided on the back switch. The switch marking faces the same direction as the front side of the steering wheel. A back switch light source is provided in the front switch assembly. The back switch light source illuminates the switch marking.
According to another aspect of the invention, a steering wheel of a vehicle that has a front side facing a driver of the vehicle and a back side opposite from the front side is provided. The steering wheel includes a front switch assembly that is provided on the steering wheel to rotate integrally with the steering wheel. The front switch assembly has a front switch facing the same direction as the front side of the steering wheel. A switch marking is provided on the front switch. A back switch is provided on the steering wheel to rotate integrally with the steering wheel. The back switch is located at a position closer to the back side of the steering wheel than the front switch assembly. A switch marking is provided on the back switch. The switch marking faces the same direction as the front side of the steering wheel. A front switch light source illuminates the switch marking on the front switch. A back switch light source illuminates the switch marking on the back switch. A circuit board is provided in the front switch assembly. The front switch light source and the back switch light source are provided on the circuit board.
In addition, present invention may be applicable to provide a switch device in a steering wheel of a vehicle. The steering wheel has a front side facing a driver of the vehicle and a back side opposite from the front side. The switch device includes a front switch that is provided on the front side of the steering wheel to rotate integrally with the steering wheel. A back switch is provided on the steering wheel to rotate integrally with the steering wheel. The back switch is located at a position closer to the back side of the steering wheel than the front switch. A switch marking is provided on the back switch. The switch marking faces the same direction as the front side of the steering wheel. A back switch light source is provided in the steering wheel to rotate integrally with the steering wheel. The back switch light source illuminates the switch marking.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.